17 month old Reverse Brindle Female Boxer in Austin, Texas

We have to find a new home for 1 of our Boxers. We bought a beautiful purebred 17 month old month female reverse brindle Boxer named Bella a few weeks ago because she is a near carbon copy of our brindle girl who we lost a few months back to cancer after having for for almost 13 years.
 
We bought her hoping she would be a good fit for our family but we do still have 2 other younger Boxers & a 14 1/2 yr old Chihuahua. Our 4 yr female female & Bella will not accept each other and both bring out the worse in each other. Bella is wonderful for our 2 yr male who is an 80 pound hyper ball of goofy Boxer energy and she was raised with a 5 yr old male and there was a 4 month old female in the home as well. Bella is also great with our Chihuahua who is as tiny as she is old and when we are out on walks she makes friends with other females and males rather easily. So the problem is a personality clash with our older female. I don't know if the mistake was bringing home an older pup or if our female is simply still mourning our deceased female; who she grew up with in her own way and that is causing the issue. 
 
Our girl is very much an ALPHA in all senses of the word and Bella is too stubborn to submit to our girl and takes her own defensive stance when our girl is trying to show her dominance. It's been a slow progress but I can walk the girls together and they will be ok out in the yard going potty or running off some energy, but the moment they come back in the house and one tries to get attention from us the other will want to start something. This usually triggers my male to get excited in his own way thinking this is a game and we worry its only going to be a matter of time before an all out fight breaks out and one of the dogs will get hurt. To keep the peace we have been keeping one of the 2 girls crated at all times, which I feel horrible for doing. Its not fair to the one being crated since she gets along great with the others and having to rotate them every few hours is very stressful. This is the only reason why we are having to place one of the girls. our girl has been with us since she was a puppy and we will never entertain the thought of placing her so we have no choice and place Bella. 
 
Bella is super sweet and very loving with us and she truly adores kids. Her last family had 3 young children none of which were old enough for school yet. She is well behaved overall, 100% housebroken and will try to open the door when she has to go potty, is crate trained (again she will try opening the door on her crate too if she has to go potty while crated so she will never have an accident in the house or crate) she knows all basic commands but being crated for so many hours a day now when she is first free she has too run off some energy and play a bit before she will truly mind you again. Give her 10-15 mins and she's back to being well trained lol! From the moment we brought her home since hasn't tried to chew on anything that wasn't given to her first..including dog toys that are already on the floor. She has zero human aggression and I have only heard her bark while playing with our male and only growl when confronting our female (in defense I should note); so if you are looking for a guardian she is not the right pup for you. 
 
We've hand fed her (that's part of how I temperament test any new comer) and she is very gentle when taking food from us and we can take her bowl, toys and treats from her. But given the reaction between her and our female I haven't attempted to feed her with the others so I can't honestly say how she would do sharing a bowl with another dog. 
 
Bella's birthday is 07/01/xxxx so she just turned a year old, and she is completely up to date on vaccines until her next birthday, she has also been on Heartgard for heartworm prevention and Frontline for flea and tick prevention. She is micro-chipped and we have the paperwork in hand to transfer the chip over; we just haven't done it yet because it was pretty clear from the start we may not be able to keep her. Bella is also still intact and we also were given a form to have her CKC registered which we also haven't touched yet so if you cared to have her registered you still can do so in your name as as well.   
 
We are asking $250 but are opened to best offer for the perfect home since we are most concerned with her finding her forever home. She'll come with her paperwork, collar, leash, and some of her food that she's currently eating. I'm including a few more photos. If you would like to see any more photos or have any questions. Also, we are actually in the Austin area but can meet closer to your area if needed in effort of finding her the perfect family.